chore(infra): update build config and deployment scripts

Update Docker configurations, nginx setup, and shared design tokens. Refresh lockfile.

Dockerfile.backend

@@ -0,0 +1,58 @@
+# Payload CMS Dockerfile - Minimal ~200MB build
+# Uses node-linker=hoisted to avoid pnpm symlinks in standalone output
+
+# Stage 1: Build
+FROM node:22-alpine AS builder
+
+WORKDIR /app
+
+# Install pnpm
+RUN corepack enable && corepack prepare pnpm@10.17.0 --activate
+
+# Copy workspace files
+COPY package.json pnpm-workspace.yaml pnpm-lock.yaml ./
+COPY apps/backend/package.json ./apps/backend/
+COPY packages/shared/package.json ./packages/shared/
+
+# Install dependencies with hoisted node_modules (no symlinks)
+# This makes standalone output work correctly
+RUN pnpm install --frozen-lockfile --config.node-linker=hoisted
+
+# Copy source files
+COPY apps/backend ./apps/backend
+COPY packages/shared ./packages/shared
+
+# Build Next.js with standalone output
+WORKDIR /app/apps/backend
+RUN pnpm run build
+
+# Stage 2: Production (minimal image)
+FROM node:22-alpine AS runner
+
+# Monorepo standalone structure: server.js is at apps/backend/server.js
+WORKDIR /app/apps/backend
+
+ENV NODE_ENV=production
+ENV PORT=3000
+
+# Combine user creation into single layer
+RUN addgroup --system --gid 1001 nodejs && \
+    adduser --system --uid 1001 nextjs
+
+# Copy standalone (preserves monorepo structure with node_modules at root)
+COPY --from=builder --chown=nextjs:nodejs /app/apps/backend/.next/standalone ./../../
+
+# Copy static assets (not included in standalone by default)
+COPY --from=builder --chown=nextjs:nodejs /app/apps/backend/.next/static ./.next/static
+COPY --from=builder --chown=nextjs:nodejs /app/apps/backend/public ./public
+
+USER nextjs
+
+EXPOSE 3000
+
+# Health check for container orchestration
+HEALTHCHECK --interval=30s --timeout=10s --start-period=30s --retries=3 \
+    CMD node -e "require('http').get('http://localhost:3000/', (r) => process.exit(r.statusCode < 500 ? 0 : 1)).on('error', () => process.exit(1))" || exit 1
+
+# Monorepo path: server.js is at /app/apps/backend/server.js
+CMD ["node", "server.js"]